화학공학소재연구정보센터
Catalysis Letters, Vol.151, No.4, 955-965, 2021
Collaborative Effect of Zinc and Phosphorus on the Modified HZSM-5 Zeolites in the Conversion of Methanol to Aromatics
In this work, the cooperative effect of Zn and P modification on the pore structure and acid properties of HZSM-5 and its catalytic performance in methanol catalytic dehydration to aromatic process were investigated. NH3-TPD and Py-IR tests reveal that introducing P and Zn can significantly decrease the acidic strength and increase the Lewis/Bronsted acid ratio of HZSM-5, which is beneficial for the aromatization of methanol rather than the hydrogen transfer reaction. Meanwhile, P doping also enlarges the pore size of HZSM-5, enhancing the coke resistance and the formation of xylene and C-9(+) aromatics. Compared to the ones modified by ZnSO4 and Zn(NO3)(2), HZSM-5 modified by Zn-3(PO4)(2) exhibits higher aromatics selectivity and lower paraffin generation, with better durability in long term operation. Furthermore, excessive Zn and P loading will result in negative impact on aromatics selectivity, and the optimal loading of ZnO and P2O5 are about 1% and 2%, respectively; higher reaction temperature and lower Si/Al lead to higher aromatics selectivity. [GRAPHICS] .